EP1674785B1 - Optoelectronic sensor and method for securing a machine - Google Patents

Abstract

The sensor monitors a protection field between an upper tool (11) and a lower tool (13) of a machine. An opening gap (17) between the upper and lower tools or between the upper tool and a work piece is closed. An interference signal is generated in case of interference of the field, where expansion of the field during working motion is less than fifty percent of the maximum monitorable field of view from the sensor. An independent claim is also included for a method for protecting a machine.

Description

The invention relates to an optoelectronic sensor according to the preamble of claim 1.

The invention further relates to a method for securing a machine according to the preamble of claim 10. Such a method is known from the document EP-A-1 281 986 known and works with a protective field whose dimensions during the entire working movement amount to less than 50% of the maximum monitored protective field.

The machines to be monitored in accordance with the invention are typically die-pressing, shearing and punching for bending, bending, cutting or punching workpieces, such as e.g. Sheet metal parts. Said first tool part is formed in this case by an upper tool having an elongated bending line or cutting edge. This upper tool is moved vertically downwards during its working movement against a lower tool, which serves as a second tool part and on which the workpiece rests or rests.

For each machining operation, the previously machined workpiece must first be removed and the new workpiece to be machined inserted into the opening gap between the tool parts. This is done manually by an operator. In order to avoid injury during the closing of the opening gap, in particular the hands of the operator, the optoelectronic sensor monitors a protective field, the typically extends below the moving upper tool in the case of a die press. This protective field has a certain extent, ie its contour extends along a two-dimensional cross-section, which lies in a plane perpendicular to the bending or cutting line, so that the sensor can respond quickly and reliably to interventions from different directions.

Such a backup of machine tools has been proven to reduce the described risk of injury. On the other hand, of course, there is the effort that the working movements of the first tool part can be performed as quickly as possible, so that the machine tool can work with a high power stroke. However, an increased power stroke is in a certain conflict with the monitoring of a large protective field, since with a large protective field, on the one hand, harmless adjustments of the workpiece by the operator can already lead to an undesired shutdown process and, on the other hand, a large amount of data must be processed in real time ,

It is an object of the invention to provide an optoelectronic sensor and a method for securing a machine, which allow a monitoring with a reduced effort.

This object is achieved by the features of claim 1 and also by a method according to claim 10.

According to the invention, it has thus been taken into account that it is not absolutely necessary for the realization of a secure monitoring function to monitor the entire field of view of the sensor during the entire working movement, but that it is perfectly adequate for most applications when the protective field is at particularly critical areas is limited, which make up in total less than 50% of the visual field of the sensor. This limitation of the protective field ensures that the amount of data to be evaluated for the monitoring function is reduced to half or less than half compared to monitoring the entire field of view, so that it is possible to significantly speed up the evaluation process and / or the reduce the evaluation to be operated circuit complexity.

If one uses the thus reduced amount of data to increase the evaluation speed, it becomes possible to operate the machine at high speed, in particular at the beginning of the working movement, during which the tool parts are still relatively quickly moved toward one another without direct action on the workpiece because even at such high speeds, the evaluation of the protective field can be done sufficiently fast in real time. This advantage can be achieved, in particular, by virtue of the fact that the active protective field is significantly smaller than the field of view of the sensor already at the beginning of the working movement, and it is particularly preferred if this condition is fulfilled at any time during the working movement of the machine.

In a particularly advantageous embodiment of the invention, a control unit is provided which is suitable for displacing the active protective field within the visual field of the optoelectronic sensor during the working movement. By means of such a control unit, it is possible to position the active protective field at any time of the working movement so that on the one hand each existing hazardous areas are adequately secured by the protective field and on the other hand, those areas are excluded from the protective field, can be intervened in the safe or within that the workpiece at his Machining must move. It can thus be an optimal protection at the same time undisturbed working movement of the machine realize.

In many applications, it makes sense if the protective field does not extend to the same extent within the anteroom and within the rear space of the machine, ie in front of and behind the cutting edge or bending line of a tool. Namely, if the protective field is arranged asymmetrically in the above manner, it is possible to increase the dimensions of the protective field, for example in the antechamber of the machine, so on the works side, from which a user can engage in the machine, with respect to the rear space, so that provides the user with improved protection.
This advantage is also achieved when working in certain applications with protective fields whose extent is more than 50% of the maximum monitorable field of view.

In extreme cases, the protective field can be arranged so that it extends, for example, only within the anteroom of the machine. Likewise, the protective field can also be completely in the back of the machine, so as to determine, for example, whether a moving from the anteroom forth in the work area of the machine body part of a user protrudes into the rear space, so then done a shutdown of the machine can.

The size of the protective field can be constant even during the entire working movement, especially when it is moved within the field of view, so that the amount of data to be processed by the evaluation unit per time unit is always the same.

According to the invention, the protective field consists of several, non-contiguous, within the field of view of the optoelectronic sensor lying, strip-shaped segments. Also, these segments can be moved by means of said control unit during the working movement within the field of view of the optoelectronic sensor. The size of the individual segments is preferably constant throughout the working movement. Due to the aforementioned division of the protective field into individual segments, it is possible to monitor a relatively large area in the end without actually including every point or every pixel of the area belonging to the protective field to be evaluated. If, for example, the individual segments are spaced apart such that the gap between the individual segments is dimensioned to be smaller than a finger width, it can nevertheless be ensured that a finger projecting into a dangerous region is reliably detected. At the same time, however, the amount of data to be processed is significantly reduced since only the data originating from the segments is to be processed and those data relating to the spaces between the segments can be disregarded.

It is advantageous if a single segment or several segments can be deactivated during a part of the working movement. In this way, for example, when bending a box, the circumstance can be taken into account that the box moves in a predictable manner into the field of view of the sensor during the bending process and, however, no shutdown of the machine is to be triggered. In this respect, those segments which relate to that region of the visual field of the sensor into which the box parts move in, for example at the end of the working movement, when the corresponding movement of the box takes place, can be deactivated.

Alternatively or additionally, the control unit can be designed so that during the working movement, the relative position of the segments to each other within the field of view of the optoelectronic sensor is changed. Such a change in the positions of the segments can be used not to monitor certain areas of the visual field of the sensor at certain stages of the working movement, but to monitor other areas, for example, more intensively. Alternatively, however, it is also possible to keep the relative position of the segments to each other constant during the entire working movement, which allows a simplified evaluation algorithm.

It is particularly preferred if the strip-shaped segments of the protective field extend parallel or perpendicular to the direction of the working movement. Likewise, however, the strip-shaped segments can also run obliquely to the direction of the working movement or have any other shapes. The use of a checkerboard pattern instead of a striped pattern is also possible. For the purposes of the invention, a checkerboard pattern also applies as a pattern which consists of a plurality of non-contiguous segments, although these segments touch each other in their corner regions.

It is also advantageous if at least two groups of segments can be activated alternately at least during a part of the working movement. Likewise, more than two segment groups can be provided, which are activated one after the other, in a regular cycle. In this case, the two or more groups of segments can complement one another to an at least substantially complete protective field, which can cover a part or even the entire area of the visual field of the optoelectronic sensor.

In this variant according to the invention, only the data of a group of segments must be evaluated in real time in succession, so that the advantages according to the invention also arise here.

Finally, the invention also extends to a method for operating the device described. In such a method, it is particularly preferred if, during the working movement, all pixels of the receiving element of the optoelectronic sensor are read out, but only the pixels assigned to the active protective field are evaluated. In contrast to their evaluation, the reading out of the pixels does not require any additional large amount of time, so that it is advantageous if, in principle, all the pixels are available for the evaluation and only those pixels are evaluated which are currently assigned to the protective field. This is particularly advantageous if the protective field changes during the working movement within the field of view of the sensor.

Fig. 1

zeigt eine schematische Frontansicht einer Gesenkbiegepresse, und

Fig 2-11

zeigen jeweils eine schematische Seiteransicht von Teilen dieser Gesentzbiegepresse mit anterschiedlichen schutzfeldern.

Fig. 12 - 15

zeigen jeweils eine schematische Seitenansicht von Teilen dieser Gesenkbiegepresse mit unterschiedlich, jeweils erfindungsgemäß gestalteten Schutzfeldern.

Further embodiments of the invention are mentioned in the subclaims. The invention will now be described by way of example with reference to the drawings.

Fig. 1

shows a schematic front view of a Gesenkbiegepresse, and

Fig. 2-11

each show a schematic side view of parts of this Gesentzbiegepresse with different protective fields.

FIGS. 12-15

each show a schematic side view of parts of this Gesenkbiegepresse with different, each inventively designed protective fields.

In the Fig. 1 shown press brake has an upper tool 11, which is a working movement vertically downwards against a lower tool 13 can be driven to bend a resting on the lower tool 13 workpiece 15. During this working movement, an opening gap 17 between the upper tool 11 and the workpiece 15 is gradually closed.

On the two sides of the upper tool 11 each have a holding arm 19 is provided. The holding arms 19 carry a transmitting device 21 and a spatially resolving receiving device 23, which are parts of an optoelectronic sensor. The transmitting device 21 has a laser diode with a transmitting optics (not shown in the figures), which expands the transmitted light of the laser diode into a light beam 25. Instead of a laser diode, any other bulbs, for example light-emitting diodes, can be used here. The receiving device 23 has a matrix receiver, which is acted upon by the light beam 25.

The light beam 25 traverses the opening gap 17 below the upper tool 11. The outline of the activated part of the receiving device 23 extending perpendicularly to the plane of the drawing thus defines within the light beam 25 a volume-shaped protective field 27 between the upper tool 11 and the lower tool 13, as will be explained below. As soon as an evaluation and control device of the sensor (not shown in the figures) detects an interruption of the light beam 25 within the protective field 27, it triggers a switch-off process for stopping the upper tool 11. As a result, an operator who, for example, inserts the workpiece 15 into the opening gap 17, is protected from injury by the upper tool 11.

The Fig. 2 to 15 in each case show the upper tool 11, the lower tool 13, the resting on it workpiece 15, the circular cross-section light beam 25 and the receiving device completely acted upon 23 in a schematic side view. Of the individual receiving elements of the receiving device 23 is in accordance with the FIGS. 2 to 15 only one different part activated. Only these activated receiving elements are thus monitored for an interruption of the light beam 25 to trigger a shutdown, if necessary. The arrangement of these activated receiving elements determines the cross section of the protective field 27. Thus, the actually monitored protective field 27 - in the FIGS. 2 to 15 each hatched drawn - within the field of view of the receiving device 23, wherein this field of view is each significantly larger than the respective protective field 27th

The circular field of view of the receiving device 23 is in the Fig. 2 to 15 dashed lines. Within this field of view, an arbitrarily designed protective field can be provided at arbitrary positions as long as its extent is less than 50% of the total area of the field of view of the receiving device 23.

The Fig. 2 to 4 each show possible embodiments of protective fields, which consist of only one strip, which has a constant position within the field of view of the sensor during the entire working movement. Such protective fields can either only in the anteroom ( 3 and 4 ) or only in the back room (not shown) or in both the anteroom and in the back room ( Fig. 2 ) of the machine. The horizontally extending, strip-shaped protective field according to Fig. 2 extends in equal parts in the antechamber and the rear space of the machine, wherein it is not located centrally between the upper tool 11 and the lower tool 13. The protective field according to Fig. 2 moves with the operation of the machine with the upper tool 11 with.

The Fig. 5 to 7 show protective fields whose dimension is less than 10% of the size of the field of view of the receiving device 23 and which each have different shapes. Fig. 5 shows a square, Fig. 6 a circular and Fig. 7 an angled shape of the protective field. These protective fields are stationary and immovable in the field of view of the receiving device 23 is arranged. Alternatively to the embodiments according to the Fig. 5 to 7 It is also possible to use any other forms of protective fields which in turn can be provided at arbitrary positions within the visual field of the receiving device 23.

According to Fig. 8 the workpiece is formed as a box 15. In this case is - as well as in the Fig. 5 to 7 - Provided a very small protective field, which according to Fig. 8 has a square shape and is positioned so that curved parts of the box 15 during the working movement does not interfere with the protective field, thus triggering an unwanted machine stop.

According to Fig. 9 can be a protective field which in Fig. 9 is shown as an example rectangular, are moved in any direction within the field of view of the receiving device 23, what the in Fig. 9 illustrate arrows shown. By such, during the working movement of the machine occurring displacement of the protective field can be ensured that the protective field is always located at the point where no intervention by a user may be made, but at the same time it is positioned so that it moves through moving areas of the workpiece 15 is not violated, so that again no unwanted stopping of the machine takes place.

Fig. 10 shows a variant of the protective field according to Fig. 9 , which is suitable for bending boxes. According to Fig. 10 the protective field can be arranged at the beginning of the working movement in the lower region of the receiving device 23 and then moved in the further course of the working movement in the direction of the upper tool 11, so as to ensure that the region of the box 15 to be bent does not unintentionally engage in the protective field.

Fig. 11 illustrates that not only protective fields with a shape according to the FIGS. 9 and 10 but also, for example, elongated, strip-shaped protective fields can be moved within the field of view of the receiving device 23 so as to be able to secure the respectively just endangered area during a working movement.

The Fig. 12 to 15 illustrate that a protective field according to the invention consists of a plurality of non-contiguous segments, wherein these segments can be located in a constant position within the field of view of the receiving device 23 ( Fig. 12 to 14 Alternatively, but also in the field of view are movable ( Fig. 15 ).

The in the Fig. 12 to 15 illustrated forms of protective fields are again shown only as examples. Any other shapes or numbers of protective field segments can be realized.

The protective field constructed of three vertical stripes according to Fig. 12 ultimately allows the monitoring of a substantially square, in Fig. 12 Dashed line area, without here all of this dashed area associated pixels of the receiving device 23 would have to be evaluated. This is achieved by that the strip-shaped segments of the protective field are arranged so close to each other that no dangerous interference can take place in the spaces formed between the segments. For example, the spacing of the individual segments may be about 14 mm, thereby ensuring that a user's finger can not enter such a gap undetected.

The in the Fig. 2 to 8 and 12 to 14 drawn stationary protective fields can either be stationary relative to the upper tool 11, but alternatively also stationary relative to the lower tool 13. In the latter case, the device would have according to Fig. 1 be modified so that the support arms 19 are coupled to the transmitting device 21 and the receiving device 23 is not with the upper tool 11 but with the lower tool 13.

LIST OF REFERENCE NUMBERS

11

upper tool

13

lower tool

15

workpiece

17

opening gap

19

holding arm

21

transmitting device

23

receiver

25

beam of light

27

protection field

Claims (12)

1. An optoelectronic sensor for the securing of a machine, in particular of a bending press, having a first tool part (11) for the carrying out of a working movement in the direction of a second tool part (13) such that, in the course of this working movement, an opening gap (17) between the tool parts (11, 13) or between a tool part (11) and a workpiece (15) can gradually be closed, wherein the optoelectronic sensor is designed for the monitoring of a protective field between the tool parts (11, 13) such that, on an intervention into the protective field, a switching signal can be generated by an evaluation unit, in particular for the interruption of the working movement, and wherein the extent of the protective field active during the working movement furthermore amounts to less than 50% of the field of view which can be monitored at a maximum by the optoelectronic sensor during substantially the total working movement,
   characterised in that
   the protective field consists of a plurality of non-contiguous strip-shaped segments disposed within the field of view of the optoelectronic sensor.
2. An optoelectronic sensor in accordance with claim 1, characterised in that a control unit is provided for the displacement of the active protective field within the field of view of the optoelectronic sensor occurring during the working movement.
3. An optoelectronic sensor in accordance with any one of the preceding claims, characterised in that the region of the protective field located in the space in front of the machine is larger than the region of the protective field located in the space behind the machine.
4. An optoelectronic sensor in accordance with any one of the preceding claims, characterised in that the protective field extends only within the space in front of the machine or within the space behind the machine; and/or in that the size of the protective field is constant during the total working movement.
5. An optoelectronic sensor in accordance with any one of the preceding claims, characterised in that the control unit is designed for the displacement of the segments within the field of view of the optoelectronic sensor which takes place during the working movement.
6. An optoelectronic sensor in accordance with claim 5, characterised in that the size of the segments is constant during the total working movement; and/or in that an individual segment or also a plurality of segments can be deactivated completely or partly during a part of the working movement.
7. An optoelectronic sensor in accordance with claim 5 or claim 6, characterised in that the control unit is designed for the changing of the relative position of the segments with respect to one another within the field of view of the optoelectronic sensor which takes place during the working movement; or in that the relative position of the segments with respect to one another is constant during the total working movement.
8. An optoelectronic sensor in accordance with any one of the preceding claims, characterised in that the strip-shaped segments extend parallel or perpendicular to the direction of the working movement.
9. An optoelectronic sensor in accordance with any one of the preceding claims, characterised in that at least two groups of segments can be activated alternately at least during a part of the working movement, with the two groups of segments in particular complementing one another to form an at least largely gap-free protective field.
10. A method for the securing of a machine, in particular of a bending press, wherein a first tool part (11) carries out a working movement in the direction of a second tool part (13) such that, in the course of this working movement, an opening gap (17) between the tool parts (11, 13) or between a tool part (11) and a workpiece (15) is gradually closed, wherein an optoelectronic sensor monitors a protective field between the tool parts (11, 13) such that, on an intervention into the protective field, a switching signal can be generated, in particular for the interruption of the working movement, and wherein the extent of the protective field active during the working movement furthermore amounts to less than 50% of the field of view which can be monitored at a maximum by the optoelectronic sensor during substantially the total working movement,
    characterised in that
    a protective field consisting of a plurality of non-contiguous strip-shaped segments disposed within the field of view of the optoelectronic sensor is monitored.
11. A method in accordance with claim 10, characterised in that all the respective pixels of the receiver element of the optoelectronic sensor are read out during the working movement, but only the respective pixels associated with the active protective field are evaluated.
12. A method in accordance with one of the claims 10 or 11, characterized by at least one method step which can be carried out using an optoelectronic sensor in accordance with any one of the claims 2 to 8.

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